Approach:
A fluorescence technique will be used to quantify larval feeding on the artificial diet modifications. This method was developed specifically for evaluating neonate western corn rootworm larval feeding on natural and synthetic blends. A non-toxic, water soluble fluorescent dye (0.1%) will be added to the liquid mixture that will be added to form the artificial diet matrix. After a defined exposure to a diet treatment, larvae will be collected, washed by dipping them briefly in distilled water, then viewed under ultra-violet light with a dissecting microscope in a darkened room. The digestive tracts of rootworm larvae fluoresce under blacklight if the larvae fed on the treated matrix and the digestive tracts do not fluoresce if larvae have not fed. Additionally, the strength of larval feeding can be determined by the intensity of the fluorescence. After determining the level of fluorescence, larva will be observed (five min) for evidence of toxicity. Each larva will be rated on a scale similar to that developed by Monke (1985), which ranges from “live” (no toxic effects), through five increasing levels of impairment, to complete mortality. Previously published methods developed by ARS and (Strnad and Dunn 1990) will be used to evaluate behavioral responses to diet.